Effect of Intensive Diabetes Management on Cardiovascular Events in the DCCT/EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications)

A significantly lower risk of heart disease can now be added to the list of proven long-term benefits of tight glucose control in people with type 1 diabetes. Researchers announced this finding today at the annual scientific meeting of the American Diabetes Association after analyzing cardiovascular (CVD) events such as myocardial infarction, stroke, and angina in patients who took part in the Diabetes Control and Complications Trial (DCCT) years ago.

“The longer we follow patients, the more we’re impressed by the lasting benefits of tight glucose control,” said Saul Genuth, M.D., of Case Western University. Dr. Genuth chairs the follow-up study of DCCT participants, called the Epidemiology of Diabetes Interventions and Complications (EDIC) study, which has been looking at the long-term effects of prior intensive versus conventional blood glucose control. “The earlier intensive therapy begins and the longer it is maintained, the better the chances of reducing the debilitating complications of diabetes.”

The DCCT was a multicenter study that compared intensive management of blood glucose to conventional control in 1,441 people with type 1 diabetes. Patients 13 to 39 years of age were enrolled in the trial between 1983 and 1989. Those randomly assigned to intensive treatment kept glucose levels as close to normal as possible with at least three insulin injections a day or an insulin pump, guided by frequent self-monitoring of blood glucose. Intensive treatment meant keeping hemoglobin A1c (HbA1c) levels as close as possible to the normal value of 6 percent or less. Conventional treatment at the time consisted of one or two insulin injections a day with daily urine or blood glucose testing. In 1993, researchers announced the DCCT’s main findings: intensive glucose control greatly reduces the eye, nerve, and kidney damage of type 1 diabetes. Tight control also lowers the risk of atherosclerosis, according to a study of DCCT participants published in 2003. But what’s most remarkable about intensive control, the researchers say, is its long-lasting value.

In results announced today, among the 1,375 volunteers continuing to participate in the study, the intensively treated patients had less than half the number of CVD events than the conventionally treated group (46 compared to 98 events). Such events included myocardial infarction, stroke, angina, and coronary artery disease requiring angioplasty or coronary bypass surgery. Thirty-one intensively treated patients (4 percent) and 52 conventionally treated patients (7 percent) had at least one CVD event during the 17 years of follow-up. The average age of participants is 45 years; 53 percent are male.

“The risk of heart disease is about 10 times higher in people with type 1 diabetes than in people without diabetes. It’s now clear that high blood glucose levels contribute to the development of heart disease,” said David Nathan, M.D., of Massachusetts General Hospital, who co-chaired the DCCT/EDIC research group and presented the results. “The good news is that intensively controlling glucose significantly reduces heart disease as well as damage to the eyes, nerves, and kidneys in people with type 1 diabetes.

DCCT and EDIC were funded by the NIDDK and other parts of the National Institutes of Health (NIH) under the Department of Health and Human Services. Genentech, Inc., also supported the studies through a Cooperative Research and Development Agreement with the NIDDK.